1. Field of the Invention
The present invention relates to a MOS (metal oxide semiconductor) type solid-state image pickup element and a method of manufacturing the same, and an electronic apparatus using the same.
2. Description of the Related Art
The scale down of a solid-state image pickup element causes such a problem that an area of a light receiving surface is reduced, an incidence efficiency is reduced, and thus sensitivity characteristics become worse. In order to solve this problem, for example, a solid-state image pickup element is proposed which has a structure adapted to condense a light by using an on-chip lens, an intra-layer lens, or the like. However, adoption of such a structure in the solid-state image pickup element results in the worse sensitivity and shading characteristics due to a loss (eclipse) of a light by a diffusion preventing layer for preventing diffusion of wirings or copper wirings provided in an upper layer of a photodiode.
Also, in addition to the structure described above, there is known a solid-state image pickup element having such a structure that a waveguide structure is provided in insulating layers formed above a photodiode. A solid-state image pickup element having this structure, for example, is described in Japanese Patent Laid-Open No. 2008-166677 (hereinafter referred to as Patent Document 1). In the solid-state image pickup element having this structure, for example, a hole portion is formed above the photodiode in a lamination structure including an insulating layer formed from a SiO2 layer (refractive index: 1.45). Also, a silicon nitride (P—SiN) layer (refractive index: 1.9 to 2.0) is thinly formed so as to cover an inner surface of the hole portion by utilizing a plasma deposition method, and a high-refractive index resin (siloxane containing therein Ti) (refractive index: 1.7) is buried in the entire hole portion through the P—SiN layer.
In the solid-state image pickup element having the waveguide structure described above, the sensitivity characteristics are enhanced as the reference index of the high-refractive index resin layer buried in the entire hole portion is higher.
In the waveguide structure described above, it is possible to expect that when the P—SiN layer formed on the inner surface having the sidewall of the waveguide is thicker, or the entire hole portion of the waveguide is filled with only the P—SiN layer having the larger refractive index, the sensitivity characteristics are enhanced in the photodiode. For this reason, there is also proposed a solid-state image pickup element having a waveguide structure based on such a structure that an entire hole portion of a waveguide is filled with only the P—SiN layer. This solid-state image pickup element having the waveguide structure, for example, is described in Japanese Patent Laid-Open No. 2006-324293 (hereinafter referred to as Patent Document 2).